I. Field of the Invention
Whole blood analysers are analysers which carry out analyses on tubes of blood containing all the elements of the blood, in contrast to analysers which work on blood plasma or serum.
II. Description of Related Art
In contrast to the analyses carried out on blood plasma or serum the blood which is to be analysed by a whole blood analyser has to be carefully mixed a very short time before the analysis. This agitation phase is absolutely necessary in order to homogenise the blood so as to re-suspend the cells which naturally settle out when the tube is motionless, and it has to be carried out in accordance with the recommendations of the standardisation committees.
This agitation phase is treated differently depending on the type of analyser used and its degree of automation. In the simplest analysers there are no agitation means in the apparatus and the agitation then has to be carried out manually by the operator prior to the analysis.
In more sophisticated analysers, and particularly in haematology equipment, the tubes are installed before analysis in agitators made up of wheels or racks.
In agitators provided with wheels the tubes of blood are placed in indentations arranged around the periphery of a wheel. Each tube is then inverted and returned to its initial position on each revolution of the wheel. The quality of the agitation is good but the automation is limited to the capacity of the wheel, which has to be changed each time capacity is reached.
In agitators provided with racks, the tubes are placed in racks before being loaded into an analyser. The analyser then arranges for the agitation of the tubes followed by the analysis and storage of the analysed racks.
In order to increase the yield and efficacy of the analyses, it is normal to add automatic conveyor belts to the analysers for carrying the tubes which are to be analysed from a storage zone to the point of analysis where they are taken over by the analyser.
The majority of automated lines use a rack-type conveying method with passing means also operating with racks. This technique is used particularly by the company Sysmex, which markets a system in which the racks are mounted on a rail which carries them from one analyser to the other, the passage to an analyser being carried out in a translatory movement. The storage and flow management of the racks are carried out by a buffer storage system. A description of this technique can be found in U.S. Pat. No. 5,232,081. The storage and flow management of the racks are provided by a storage apparatus which makes it possible to adapt the movement of a rack in the storage system on the conveyor to the analysing sequence. The racks have proved effective for analyses which do not require a second passage into the analyser, as they make it possible to achieve high analysis rates. However, this system lacks flexibility if for any reason a tube has to be fed into the analyser a second time. In this case the entire rack containing the tube in question has to be returned to the storage device in order to be sent back into the analyser.
The use of racks in an automated line also requires restrictive arrangements in terms of changes of direction and turns required of the conveyor belt. Examples of solutions which set out to solve these problems are described in particular in U.S. Pat. No. 5,366,062 and U.S. Pat. No. 5,380,488.
Another problem concerns reading the information written on the label of each of the tubes, owing to the fact that the automated line has to have readers for reading the labels on each tube through the rack. A number of technical solutions have been proposed for solving this problem. Thus, for example, U.S. Pat. No. 6,081,326 and U.S. Pat. No. 5,286,959 describe a device for rotating the tube on itself inside the rack in order to position its label in front of an optical reader positioned in front of a slot in the rack. According to another embodiment described in US Patent Application 2002/0100806, a lug located in the indentation containing the tube enables the label on the tube to be positioned in front of a window in the rack to allow an optical reader to read the contents of the label. These patents clearly show the complexity and difficulty in reading a label on a tube stored in a rack.
Moreover, the use of racks in an automated line has its limits when there is a need to manipulate or select a specific tube in order to run a new series of tests on it. The diagnosis and new measuring techniques show that a tube must be capable of being re-tested or undergoing a new series of tests after a first disputed analysis. In this context the automated line using racks is of no value and the use of an automated line with a mono-tube support appears to be better suited to the needs of modern laboratories.
Automated lines with a mono-tube support in the majority of cases are lines comprising conveyor belts. Descriptions of this type of line are to be found in U.S. Pat. Nos. 6,374,989 and 5,941,366. In U.S. Pat. No. 5,224,585, the conveyor belt is used as a magnetic support enabling the supports to remain adhered to the belt during both horizontal and vertical movements.
In the field of automated lines, and particularly for biochemical apparatus, chaining techniques are also used. However, the reaction times of these apparatus are quite long. A complex chaining system which combines a tube support with a receptacle integrally attached to the chain and allowing a chemical reaction to be carried is described in particular in U.S. Pat. No. 6,358,471. Another chaining system which can be used to convey tubes in order to transport them to a whole blood analyser is described in U.S. Pat. No. 4,944,924. U.S. Pat. No. 5,582,795 also describes a tube chain which combines the tubes with a belt.
These chaining techniques are difficult to apply to automated lines, notably because they do not allow for the removal of a tube, or a tube with its support, without producing problems in the flow of tubes. Similarly, returning a tube to one of the apparatus requires the whole chain to run to the apparatus which is to be used. The chain described in the above-mentioned patents appears to be an inflexible technical solution and certainly not adapted to modern automated lines working with whole blood.
Other patents or patent applications such as U.S. Pat. No. 5,623,415, U.S. Pat. No. 4,039,288, U.S. Pat. No. 5,623,415, WO 95/03548 and WO 98/01760, describe the use of analytical equipment comprising mono-tube rails, but these appear to be intended solely for conveying tubes and do not disclose any pre-analytical means enabling the tubes to be agitated, for example, before analysis.
The category of unitary lines chiefly has the advantage that each tube can be treated as a different entity from the other tubes. To do this it requires that its own needs be met in terms of analysis, checking and additional examination, notably the possibility of easily making use of “conditioned analysis” or “reflex testing” which consists in automatically carrying out complementary examination if this can logically assist the diagnosis. This is a source of effectiveness in arriving at a diagnosis and reducing costs by doing away with any additional examinations which are irrelevant to the diagnosis.